scholarly journals Evolutions of Oil Generation and Expulsion of Marine-Terrestrial Transitional Shales: Implications From a Pyrolysis Experiment on Water-Saturated Shale Plunger Samples

2021 ◽  
Vol 9 ◽  
Author(s):  
Qizhang Fan ◽  
Peng Cheng ◽  
Xianming Xiao ◽  
Haifeng Gai ◽  
Qin Zhou ◽  
...  
Keyword(s):  
Theoretical Basis ◽  
Oil And Gas ◽  
Evolution Model ◽  
Shale Oil ◽  
Oil Generation ◽  
Oil And Gas Resources ◽  
Pyrolysis Experiment ◽  
Shale Reservoirs ◽  
Water Saturated ◽  
Oil Expulsion

Shale reservoirs are characterized by self-generation and self-accumulation, and the oil generation and expulsion evolution model of organic-rich shales is one of important factors that obviously influence the enrichment and accumulation of shale oil and gas resources. At present, however, relevant studies on marine-terrestrial transitional shales are inadequate. In this study, a pyrolysis experiment was performed on water-saturated marine-terrestrial transitional shale plunger samples with type Ⅱb kerogen to simulate the evolutions of oil generation and expulsion. The results indicate that marine-terrestrial transitional shales have wider maturity ranges of oil generation and expulsion than marine and lacustrine shales, and the main stages of oil expulsion are later than those of oil generation, with corresponding Ro values of 0.85%–1.15% and 0.70%–0.95%, respectively. Although the oil generation and expulsion process induced a fractionation in compositions between the expelled and retained oils, both the expelled and retained oils of marine-terrestrial transitional shales are dominated by heavy compositions (resins and asphaltenes), which significantly differs from those of marine and lacustrine shales. The kerogen of marine-terrestrial transitional shales initially depolymerized to transitional asphaltenes, which further cracked into hydrocarbons, and the weak swelling effects of the kerogen promoted oil expulsions. The oil generation and expulsion evolutions of these shales are largely determined by their organic sources of terrigenous higher organisms. This study provides a preliminary theoretical basis to reveal the enrichment mechanism of marine-terrestrial transitional shale oil and gas resources.

Geology, resource potentials, and properties of emerging and potential China shale gas and shale oil plays

2015 ◽  
Vol 3 (2) ◽  
pp. SJ1-SJ13 ◽  
Author(s):  
Shu Jiang ◽  
Jinchuan Zhang ◽  
Zhiqiang Jiang ◽  
Zhengyu Xu ◽  
Dongsheng Cai ◽  
...  
Keyword(s):  
South China ◽  
Shale Gas ◽  
Oil And Gas ◽  
Northwest China ◽  
Shale Oil ◽  
Yangtze Platform ◽  
Lower Paleozoic ◽  
High Maturity ◽  
Shale Reservoirs ◽  
Gas Potential

This paper describes the geology of organic-rich shales in China, their resource potentials, and properties of emerging and potential China shale gas and shale oil plays. Marine, lacustrine, and coastal swamp transitional shales were estimated to have the largest technically recoverable shale gas resource (25.08 trillion cubic meters or 886 trillion cubic feet) and 25 to 50 billion barrels of technically recoverable shale oil resource. The Precambrian Sinian Doushantuo Formation to Silurian Longmaxi black marine shales mainly accumulated in the intrashelf low to slope environments in the Yangtze Platform in South China and in the Tarim Platform in northwest China. The marine shales in the Yangtze Platform have high maturity (Ro of 1.3%–5%), high total organic carbon (mainly [Formula: see text]), high brittle-mineral content, and have been identified as emerging shale gas plays. The Lower Paleozoic marine shales in the Upper Yangtze area have the largest shale gas potential and currently top the list as exploration targets. The Carboniferous to Permian shales associated with coal and sandstones were mainly formed in transitional depositional settings in north China, northwest China, and the Yangtze Platform in south China. These transitional shales are generally rich in clay with a medium level of shale gas potential. The Middle Permian to Cenozoic organic-rich lacustrine shales interbedded with thin sandstone and carbonate beds are sporadically distributed in rifted basins across China. Their main potentials are as hybrid plays (tight and shale oil). China shales are heterogeneous across time and space, and high-quality shale reservoirs are usually positioned within transgressive systems tract to early highstand systems tract intervals that were deposited in an anoxic depositional setting. For China’s shale plays, tectonic movements have affected and disrupted the early oil and gas accumulation, making tectonically stable areas more favorable prospects for the exploration and development of shale plays.

An emerging shale gas play in the Northern Territory

2012 ◽  
Vol 52 (2) ◽  
pp. 672
Author(s):  
Ray Johnson ◽  
Geoff Hokin ◽  
David Warner ◽  
Rod Dawney ◽  
Mike Dix ◽  
...  
Keyword(s):  
Shale Gas ◽  
Oil And Gas ◽  
Mineral Exploration ◽  
Northern Territory ◽  
Gas Flows ◽  
Oil And Gas Resources ◽  
Unconventional Oil And Gas ◽  
Shale Reservoirs ◽  
Drill Holes ◽  
Live Oil

As attention to unconventional oil and gas resources increases, historical oil and gas flows in shale reservoirs across the world are being given renewed attention. Such is the case of the shaly and carbonate deposits of the McArthur and Nathan groups in the Northern Territory. The Batten Trough is a Proterozoic depocenter with potential for a shale gas play in the Barney Creek Shale and potential for conventional gas accumulations in the underlying Coxco Dolomite. This Barney Creek Shale gas play is evidenced by a number of mineral exploration drill holes that encountered live oil and gas shows within the McArthur Group. The most prominent was a mineral exploration hole drilled at the Glyde River prospect by Amoco in 1979. This well reportedly flowed gas and condensates at 140 psi for six months before it was sealed at the surface, which certainly shows permeability values greater than micro-darcies reported for many North American shale plays; thus, an exploration program of this prospective area has been planned by Armour Energy in EP 171 on several targets adjacent to the Emu Fault Zone near both Glyde and Caranbirini, along with other anticline related targets adjacent to the Abner Range. This extended abstract details how the targets were identified, the plan for data acquisition (e.g. seismic, drilling, logging and testing), and the proposed completion strategy to test this highly prospective target.

Eromanga (Queensland) exploration–new concepts for an old basin

2011 ◽  
Vol 51 (1) ◽  
pp. 333
Author(s):  
David Lowry ◽  
David Evans
Keyword(s):  
Oil And Gas ◽  
Oil Field ◽  
Secondary Migration ◽  
New Concepts ◽  
Oil Generation ◽  
And Migration ◽  
Oil Expulsion ◽  
Sonic Logs ◽  
Southern Flank ◽  
Eromanga Basin

Eromanga Basin exploration surged in Queensland after the discovery of the Jackson field in 1982, but has ebbed over the last 20 years. Perceived exploration risks are: • Oil generation and migration peaked in the mid-Cretaceous before much of the anticlinal structuring, so that modern structure is an uncertain guide to Cretaceous migration paths. • Permian coals are generally credited with sourcing most of the oil and gas in the Cooper-Eromanga Basin. In Queensland, the Permian largely drains to the southern flank and the northern flank is thought to have a high charge risk. This study covers 100,000 km2. It used sonic logs to determine the amount of Tertiary erosion and thus allows the preparation of structure maps restored to mid-Cretaceous time. Maturity maps of the Birkhead and Poolowanna Formations were computed from a reflectance/restored temperature algorithm based on 50 wells. Source rock thickness maps and an oil expulsion model based on Pepper and Corvi (1995a, 1995b) then allowed oil expulsion to be mapped regionally. The study produces the key results that could be expected from 3D earth modelling, but with great savings in time and money. The study demonstrates an oil kitchen at both Poolowanna and Birkhead stratigraphic levels in the vicinity of Tanbar–1. Secondary migration losses are speculative, but modelling shows that hundreds of millions of barrels of oil from each formation have migrated west towards the Curalle ridge, north to Inland and Morney, and southeast to Mt Howitt. The Inland oil field is presently an isolated anomaly on the northwest flank of the basin, but this study suggests that further exploration in the area could be successful.

scholarly journals Assessment of Eagle Ford Shale Oil and Gas Resources

2013 ◽  
Author(s):  
Xinglai Gong ◽  
Yao Tian ◽  
Duane A. McVay ◽  
Walter B. Ayers ◽  
John Lee
Keyword(s):  
Oil And Gas ◽  
Shale Oil ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Oil And Gas Resources

Geochemical evidence for oil and gas expulsion in Triassic lacustrine organic-rich mudstone, Ordos Basin, China

2017 ◽  
Vol 5 (2) ◽  
pp. SF41-SF61 ◽  
Author(s):  
Tongwei Zhang ◽  
Xiangzeng Wang ◽  
Jianfeng Zhang ◽  
Xun Sun ◽  
Kitty L. Milliken ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Ordos Basin ◽  
Organic Content ◽  
X Ray Diffraction ◽  
Deep Well ◽  
Stacking Pattern ◽  
Oil Generation ◽  
Oil Expulsion ◽  
Rock Eval ◽  
Thermal Volume Expansion

Forty-six core samples were collected from a deep well that penetrated organic-rich layers of the Chang 7, 8, and 9 members of the Yanchang Formation (Fm) in the Ordos Basin. Tests for total organic content (TOC), Rock-Eval pyrolysis, X-ray diffraction (XRD) mineralogy, and molecular composition of gases released from rock crushing were conducted. Analytical results indicate that TOC and clay contents are elevated. The organic matter (OM)-rich mudstone in the Triassic Yanchang Fm suggests good-to-excellent source potential for oil generation. Its thermal maturity is in the oil window. Strong petroleum expulsion occurred from the upper part of the approximately 13 m (42.6 ft) thick Chang 7 member, and for the Chang 8 and Chang 9 members, resulting in low free oil and low methane ([Formula: see text]) concentration in these OM-rich intervals. A combination of sandstone and thin organic-rich mudstone layers is a perfect hybrid lithology stacking pattern for petroleum expulsion. The thickness for effective source rock, approximately 10–12 m (32.8–39.3 ft), varied with sandstone/mudstone lithology stacking pattern. In contrast, limited or no oil expulsion occurred in the lower part of Chang 7 member, a 25 m (82 ft) thick organic-rich interval, which is indicated by high free oil and high [Formula: see text] concentration. A [Formula: see text]-TOC plot can be used to differentiate generated gas, retained gas in OM-rich mudstones, and migrated gas in permeable sandstone beds. We have developed a conceptual model for petroleum expulsion from OM-rich thin versus OM-rich thick layers. Compaction and thermal volume expansion of oil generated from OM may play an important role in petroleum expulsion in OM-rich mudstones. The estimated petroleum expulsion efficiency is approximately 70% and 35% for thin and thick OM-rich mudstone layers, respectively. The redistributed OM in clay-dominated rock assemblage likely forms the preferred migration path to petroleum expulsion.

Prospects and Challenges of Developing Unconventional Petroleum Resources in the Anambra Inland Basin of Nigeria

2016 ◽  
Author(s):  
K. Mosto Onuoha ◽  
Chidozie I. Dim
Keyword(s):  
Shale Gas ◽  
Oil And Gas ◽  
Petroleum Industry ◽  
Organic Content ◽  
Shale Oil ◽  
Thermal Maturity ◽  
Total Organic Content ◽  
Anambra Basin ◽  
Petroleum Resources ◽  
Oil And Gas Resources

ABSTRACT The boom in the development of unconventional petroleum resources, particularly shale gas in the United States of America during the last decade has had far reaching implications for energy markets across the world and particularly for Nigeria, a country that traditionally has been Africa’s leading crude oil producer and exporter. The Cretaceous Anambra Basin is currently the only inland basin in Nigeria where the existence of commercial quantities of oil and gas has been proven (outside the Tertiary Niger Delta Basin). The possibility of similarly finding commercially viable resources of unconventional petroleum resources in the basin appears quite attractive on the basis of the existence of seepages of shale oil and presence of coal-bed methane in some of the coal seams of the Mamu Formation (Lower Coal Measures) in the basin. This paper presents the results of our preliminary assessment of the shale oil and gas resources of the Anambra Basin. Our main objective is to locate the zones of very high quality plays within the basin, focusing on their depositional environments (whether marine or non-marine), areal extent of the target shale formations, gross shale intervals, total organic content, and thermal maturity. Data on the total organic content (TOC %, by weight) and thermal maturity of shales from different wells in the basin show that many of the shales have high TOCs (i.e greater than 2%) comparable to known shale gas and shale oil plays globally. Shale oil seepages are known to occur around Lokpanta in south-eastern Nigeria, but there is a general predominance of gas-prone facies in our inland basins indicating good prospects for finding unconventional petroleum in this and other Nigerian inland sedimentary basins. The main challenge to the exploration of unconventional resources in Nigeria today has to do with the absence of the enabling laws and regulatory framework governing their exploration and subsequent exploitation. The revised Petroleum Industry Bill (PIB) currently under consideration in the National Assembly is expected to introduce drastic and lasting changes in the way the petroleum industry business is conducted in the country, but all the provisions of the draft law pertain mainly to conventional oil and gas resources.

scholarly journals Classification and evaluation criteria of shale oil and gas resources: Discussion and application

2012 ◽  
Vol 39 (2) ◽  
pp. 268-276 ◽  
Author(s):  
Shuangfang LU ◽  
Wenbiao HUANG ◽  
Fangwen CHEN ◽  
Jijun LI ◽  
Min WANG ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Evaluation Criteria ◽  
Shale Oil ◽  
Oil And Gas Resources
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